The present invention relates to permanent magnet motors.
A motor comprises a multi-pole ring-shaped magnet that rotates relative to a stator. The stator comprises multiple coils toroidally-wound about a ring-shaped core and sequentially spaced from each other along the circumference of the core.
In accordance with the present invention, an electrical machine comprises a magnetically permeable core. The core is elongated to thereby define a lengthwise direction and a profile that is transverse to the lengthwise direction. Coils are wound about the core profile and sequentially disposed along the lengthwise direction. The core profile has a surface that is bowed outward.
In a preferred embodiment, the electrical machine further comprises an axis of rotation. The elongated core is ring-shaped and is centered on the axis. The coils are toroidally wound about the core and sequentially disposed about the axis. A cavity extends lengthwise through the core, and two ports extend from the cavity to outside the core. An elongated magnet is parallel with the core and has a magnet profile in which a side surface overhangs the core profile. The core profile is surrounded on three or four sides by a magnet. The magnet profile has a surface that is bowed inward. The inwardly-bowed surface of the magnet is adjacent and facing the outwardly-bowed surface of the core, such that the spacing between the magnet and the core is uniform along at least a portion of the bowed-out surface of the core profile. At least one of the coils consists essentially of a single layer of turns of wire and is formed of rectangular wire. Brackets are installed about the coil-free spaces. The brackets are configured to provide a flat peripheral surface defined by the peripheral surfaces of the coils and the brackets.